Observation or diagnosis of internal hollow organ using an electronic endoscope is a widely disseminated method of diagnosis at present. By virtue of its direct feature of observation, the method is ready to discriminate normal tissue and lesioned part, and for which continuous efforts have been directed to improve quality of captured image.
On the other hand, besides so-called videoscope, diagnostic equipments based on various optical principles and ultrasonic diagnostic equipments have been proposed, and a part of which have been put into practical use.
In particular, there has been proposed a fluorescence imaging endoscope system which uses fluorescent light to acquire information invisible to naked eyes to configure an fluorescent image, and displays it so as to be overlapped with a visible image (for example, Patent Document 1). This sort of system will be useful for early detection of malignant tumor, and is counted on greatly.
Another known method, although without configuring the fluorescent image, is such as acquiring intensity information of fluorescence, so as to determine the status of tissue (for example, Patent Document 2). Most of this type of methods are configured to acquire fluorescence without using an image sensor mounted on the electronic endoscope.
Known types of a diagnosing element for enabling the fluorescent diagnosis, or “probe”, include those guided into body through a forceps channel of the endoscope, and those integrated with the endoscope (note that the forceps channel means a tunnel-like path allowing a treatment tool such as forceps or catching net to pass therethrough, also referred to as a working channel, insertion channel or the like.). The probes for fluorescence observation described in Patent Documents 1 and 2 are to be inserted into body while being inserted through the forceps channel of the endoscope.
For inspection inside human body, the probe is sometimes required to be simplified in the structure thereof, in view of thinning the probe for reducing physical burden on patients and making the probe disposable aiming at preventing infection or facilitating the inspection. While the configuration of the probe may possibly be simplified by making the fiber available both for illumination and receiving, or omitting the light receiving fiber, it is indispensable for accurate measurement to use a illumination light guide for guiding therethrough an excitation light, and a receiving light guide for acquiring fluorescence, for either types, even for the case where the probe is used independently from the endoscope. As a configuration having both of illumination fiber and light receiving fiber, Patent Document 3 describes an endoscope system having a center fiber for guiding the illumination light, and a plurality of light receiving fibers arranged therearound.